Ice-minus bacteria

Ice-minus bacteria is a nickname given to a variant of the common bacterium Pseudomonas syringae (P. syringae). This strain of P. syringae lacks the ability to produce a certain surface protein, usually found on wild-type "ice-plus" P. syringae. The "ice-plus" protein (Ina protein, "Ice nucleation-active" protein) found on the outer bacterial cell wall acts as the nucleating centers for ice crystals. This facilitates ice formation, hence the designation "ice-plus." The ice-minus variant of P. syringae is a mutant, lacking the gene responsible for ice-nucleating surface protein production. This lack of surface protein provides a less favorable environment for ice formation. Both strains of P. syringae occur naturally, but recombinant DNA technology has allowed for the synthetic removal or alteration of specific genes, enabling the creation of the ice-minus strain.

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Economic importance:

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The success of the agricultural world is heavily dependent on the weather. Cold weather conditions are directly responsible for the appearance of frost on plants and most importantly, crops. In the United States alone, it has been estimated that frost accounts for approximately $1 billion in crop damage each year. As P. syringae commonly inhabits plant surfaces, its ice nucleating nature incites frost development, freezing the buds of the plant and destroying the occurring crop. The introduction of an ice-minus strain of P. syringae to the surface of plants would incur competition between the strains. Should the ice-minus strain win out, the ice nucleate provided by P. syringae would no longer be present, lowering the level of frost development on plant surfaces at normal water freezing temperature (0oC). Even if the ice-minus strain does not win out, the amount of ice nucleate present from ice-plus P. syringae would be reduced due to competition. Decreased levels of frost generation at normal water freezing temperature would translate into a lowered quantity of crops lost due to frost damage, rendering higher crop yields overall.

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Controversy

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At the time of Dr. Lindow's work on ice-minus P. syringae, genetic engineering was considered to be very controversial. The controversy primarily revolved around fears of introducing new organisms that may permanently disrupt the ecosystem. The fear was that the introduction of ice-minus bacteria to the environment would eliminate bacterial and plant varieties. This was true in the case of the gypsy moth's accidental introduction into the U.S. Without a predator in the U.S., the gypsy moth is still causing overwhelming destruction to the hardwood forests of northeastern U.S.

Text Source: Wikipedia Liscence NGU